ethtool: ioctl: Fix out-of-bounds warning in store_link_ksettings_for_user()

Fix the following out-of-bounds warning:

net/ethtool/ioctl.c:492:2: warning: 'memcpy' offset [49, 84] from the object at 'link_usettings' is out of the bounds of referenced subobject 'base' with type 'struct ethtool_link_settings' at offset 0 [-Warray-bounds]

The problem is that the original code is trying to copy data into a some struct members adjacent to each other in a single call to memcpy(). This causes a legitimate compiler warning because memcpy() overruns the length of &link_usettings.base. Fix this by directly using &link_usettings and _from_ as destination and source addresses, instead.

This helps with the ongoing efforts to globally enable -Warray-bounds and get us closer to being able to tighten the FORTIFY_SOURCE routines on memcpy().

---
 net/ethtool/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 27f1c5224acb..3fa7a394eabf 100644
@@ -489,7 +489,7 @@ store_link_ksettings_for_user(void __user *to,
 {
 	struct ethtool_link_usettings link_usettings;
 
-	memcpy(&link_usettings.base, &from->base, sizeof(link_usettings));
+	memcpy(&link_usettings, from, sizeof(link_usettings));
 	bitmap_to_arr32(link_usettings.link_modes.supported,
 			from->link_modes.supported,
 			__ETHTOOL_LINK_MODE_MASK_NBITS);

2.27.0